Production of acrylic acid esters



United States Patent 3,060,227 PRODUCTION 0F ACRYLIC ACID ESTERS RobertStadler, Heidelberg, and Hans Lautenschlager, Ludwigshafen (Rhine),Germany, assignors to Badische Anilin- & Soda-Fabrik Aktiengesellschaft,Ludwig hafen (Rhine), Germany No Drawing. Continuation of applicationSer. No. 714,494, Feb. 11, 1958. This application May 5, 1961, Ser. No.107,920

Claims priority, application Germany Feb. 23, 1957 8 Claims. (Cl.260-486) This invention relates to a process for the production ofacrylic acid esters from acetylene, carbon monoxide, and alcohols in thepresence of suitable catalysts. The special object of the invention isto provide a further improvement in the acrylic acid esters synthesisaccording to W. Reppe in which acetylene, carbon monoxide, and loweralcohols are reacted in the presence of carbonylforming metals or theircompounds at elevated temperatures and under increased pressure.

The halides of carbonyl-forming metals, especially nickel halides, incombination with a copper halide as activator, have proved to beparticularly suitable catalysts in the production of acrylic acid estersaccording to W. Reppe. The catalyst is dissolved or suspended in aninert oxygen-containing organic solvent which is used in excess.

The copending US. application Ser. No. 703,506, filed December 18, 1957by Robert Stadler and Friedrich Becke describes a process for theproduction of acrylic acid esters in which acetylene and carbon monoxideare reacted with alcohols or phenols at elevated temperature and underincreased pressure in the presence of catalytic amounts of a halide of acarbonyl-forming metal and small amounts of a heavy metal, especially aheavy metal halide, as activator, the reaction being carried out in theabsence of an organic solvent but in the presence of a compoundcontaining at least one carboxylic group. Among the compounds of thattype acrylic acid has proven to be particularly suitable.

We have now found that in the said process for the production of acrylicacid esters from lower aliphatic alcohols particularly satisfactoryresults can be obtained if acrylic acid which is formed in the course ofthe reaction from the aqueous reaction medium, is used as the carboxylicgroup containing compound.

That means that the reaction medium need not contain acrylic acid oranother compound containing a carboxylic group from the start. It isquite sufiicient if the acrylic acid is formed during the course of thereaction from water which is added to the reaction medium at thebeginning of the reaction.

The water may be supplied to the reaction medium either separately ormixed with the alcohol. It is advantageous to use about 4 to 12 percentof water with reference to the amount of the alcohol used. Largeramounts of water, it is true, would promote the formation of acrylicacid, but the formation of esters would be rendered more difiicultbecause the mixed gas, i.e. a mixture of equivalent amounts of acetyleneand carbon monoxide,

' dissolves with greater difiiculty as the water content increases. Itis an advantage, however, that when using alcohol containing a largeamount of water it is not necessary to remove the Water previously.

As catalysts there are especially suitable the halides ofcarbonyl-forming metals, especially nickel halides, for examplenickel-(2)-chloride, bromide and iodide, and complex compounds ofnickel, as for example nickel acetonyl-acetonate, the nickelbromide-triphenyl phosphine-alkyl bromide complex, and similarcompounds. When using nickel acetonyl-acetonate as heavy metal compoundit is preferable to add a halide of the heavy 3,060,227 Patented Oct.23, 1962 metal. There may be used however the carbonyl-forming metalsthemselves or their halogen-free compounds in admixture with halogen orhalogen compounds. These compounds may be dissolved in small amounts ofwater before they are added to the alcohol. Depending on the nature andamount of the activator added, the amount of catalyst should preferablybe from about 0.01 to 1 percent with reference to the amount of alcoholintroduced; the usual quantity is between 0.05 and 0.1 percent.

For the activation of the catalyst only very small amounts of a heavymetal or a heavy metal compound are required, for example 3 to 20percent of the amount of catalyst. Copper and mercury halides, e.g.copper iodide, copper bromide, or other copper compounds, such as coppercyanide or copper acetonyl-acetonate, or mercury iodide, have provedespecially effective. Very active catalysts are for example nickelbromide and cuprous iodide.

It is often advantageous to add hydrogen halides, for example HCl orHBr, to the reaction mixture. The hydrogen halide may be added inquantities of about 0.01 to 1 percent with reference to the weight ofthe alcohol introduced. The amount of the hydrogen halide thuscorresponds to the amount of catalyst used. By the addition of hydrogenhalide the throughput can be further increased and paler reactionliquids can be obtained.

The activating action of copper is so great, that even minute amounts ofcopper cause considerable action in the presence of acrylic acid, whichis formed in the course of the reaction from the water, which is presentin the reaction medium at the beginning of the reaction.

A smaller activation of the catalyst is obtained by the addition ofcompounds of other heavy metals, especially their halogen compounds. Assuch there may be used zinc iodide, cadmium iodide, lead iodide orchromium iodide. The simultaneous use for example of cadmium iodide andzinc iodide gives better activation than addition of the said compoundsby themselves. Accordingly the copper compound used for activating thecatalyst can also be partly replaced by one or more of the other heavymetal compounds mentioned above.

Suitable initial materials for the process according to this inventionare monohydric or polyhydric aliphatic alcohols, for example loweraliphatic alcohols containing 1 to 4 carbon atoms, such as methanol,ethanol, propanol, normal butanol, isobutanol or ethylene glycol,glycerine, and the like. When two different alcohols are present at thesame time, the corresponding acrylic acid esters are formed side byside. The higher alcohol is thereby preferentially converted into thecorresponding acrylic acid ester. Thus for example a mixture of ethylacrylate and normal butyl acrylate is obtained from a mixture of ethylalcohol and normal butanol.

The reaction conditions correspond to those usual in the synthesis ofacrylic acid esters according to Reppe. The working temperature isbetween 100 and 250 C. The partial pressure of the acetylene should beabove 5 atmospheres, preferably between 10 and atmospheres. The processcan be carried out both continuously and discontinuously.

At the beginning of the reaction the temperature should be for exampleabout 10 to 20 C. higher than is necessary in the conventionalesterification process, in order to effect an initial acceleration ofthe formation of acrylic acid. As soon as sufficient acrylic acid hasbeen formed the temperature can be lowered to the usual reactiontemperature.

The parts specified in the following examples, which are illustrativerather than limitative, are parts by weight and the percentagesspecified are percentages by weight unless otherwise stated. Parts byvolume are in the same ratio to parts by weight as the liter is to thekilogram.

The term mixed gas used in the examples means a gas mixture consistingof equal parts by volume of carbon monoxide and acetylene.

Example 1 100 parts of a solution which contains 3.5 percent of water,0.4 percent of nickel-2-bromide, and 0.17 percent of copper iodide innormal butanol are placed in a shaking autoclave. The autoclave isrinsed with nitrogen. Then 24 excess atmospheres of the mixture ofacetylene and carbon monoxide are forced in and the autoclave is bydistillation there can be isolated 96 parts of butyl acrylate and 3.46parts of acrylic acid. The distillation residue amounts to 14 percentwith reference to the amount of ester.

Example 2 83 parts of normal butanol which contains 12 percent of water,0.4 percent of nickel-Z-bromide, 0.1 percent of cuprous iodide, and 0.2percent of zinc bromide are placed in a shaking autoclave. 0.1 part ofhydroquinone is added as stabilizer for the normal butyl acrylate to beformed. After rinsing with nitrogen and forcing in 24 excess atmospheresof mixed gas the autoclave is heated. The autoclave pressure first risesto 33 excess atmospheres'and then falls when a temperature of 195 C. hasbeen reached. The autoclave is kept at a temperature of about 205 C. forthree hours and the pressure kept between 39 and 63 excess atmospheresby continuously forcing in of mixed gas. The autoclave contains 136parts of a reaction liquid with a density of 0.91. By distillation thereare obtained 81.5 parts of butyl acrylate and 9.65 parts of acrylicacid. The distillation residue amounts to 17.6 percent of the esterformed.

' Example 3 1,420 parts of pure ethyl alcohol, 5.0 parts of nickel-2-bromide, 0.5 part of copper bromide, 175 parts of water, and 1 part ofhydroquinone (as stabilizer) are charged into a stirring autoclave ofstainless steel. After rinsing with nitrogen, 24 excess atmospheres ofmixed gas are forced in and the autoclave is heated to 200 C. whilestirring.

The temperature in the autoclave is kept at 200 to 206 C. for 3 hoursand the pressure is kept between 45 and 58 excess atmospheres by forcingin mixed gas.

2,640 parts of a pale brown clear liquid without sediment are obtained.By distillation, 1,560 parts (i.e. 59.3 percent) of ethyl acrylate and167 parts (i.e. 6.3 percent) of acrylic acid can be isolated therefrom.11.8 percent with reference to the amount of ester remain in theresidue.

Example 4 45 atmospheres of mixed gas are forced into a vertical tube ofstainless steel having a capacity of 2.8 liters. 450 cubic centimetersper hour of ethyl alcohol containing 12 percent of water in which 0.2percent of nickel- 2-bromide and 0.05 percent of copper-(D-iodide havebeen dissolved, are continuously forced in. The reaction chamber is keptat 195 C. 50 normal liters per hour of residual gas are withdrawn inorder to avoid accumulation of gaseous byproducts. 610 cubic centimetersof a pale green reaction product are obtained per hour. 200 parts ofthis product are distilled. At atmospheric pressure nothing passes overup to an internal temperature of 100 C. Then at a pressure of 450 mm. Hgthere are obtained between 53 and 56 C. 169 parts of a fraction whichcontains 53 percent of ethyl acrylate. This fraction contains no acrylicacid. As a second fraction there are obtained 21 parts of a fractioncontaining 66 percent of acrylic acid and 27 percent of ethyl acrylate,which passes over at a pressure of 12 mm. Hg between 55 and 76 C. 10parts remain in the residue as a pale brown oil. If into the abovedescribed apparatus, in which the reaction for the formation of ethylacrylate is already proceeding, the ethyl alcoholic contact solutioncontaining 12 percent of water is no longer forced in, but a contactsolution which, besides ethanol, contains only 0.5 percent of water, theformation of ethyl acrylate slowly comes to a standstill. After 14 hoursthe reaction product still contains 0.4 percent of acrylic acid and 26percent of ethyl acrylate, and after 24 hours no acrylic acid and only3.6 percent of ethyl acrylate.

Example 5 The procedure of Example 4 is followed with the differencethat 300 cubic centimeters per hour of an ethyl alcoholic contactsolution containing 22 percent of water is forced continuously into thetube. 410 cubic centimeters per hour of a pale green reaction productare ob tained. From 200 parts of this product, by distillation, thereare obtained as the fraction 141 parts which pass over between 60 and 65C. at 450 mm. Hg and contain 55 percent of ethyl acrylate. The secondfraction is obtained at a pressure of 28 mm. Hg between 57 and 77 C. andconsists of 71 percent of acrylic acid and 19.5 percent of ethylacrylate. 11.5 parts remain in the residue.

Example 6 A mixture of 0.2 percent of nickel-Z-bromide, 0.05 percent ofcopper-(D-iodide, and 9 percent of water in normal butanol iscontinuously reacted at 205 C. and 28 mm. Hg pressure with acetylene andcarbon monoxide as described in Example 4. By forcing 350 cubiccentimeters of the mixture into the reaction tube per hour, there areobtained 440 cubic centimeters per hour of a pale yellow reactionproduct. By distillation in vacuo there are obtained therefrom 189 partsof a distillate which contains 59.5 percent of butyl acrylate and 4percent of acrylic acid as well as 11 parts of a pale yellow viscousoil.

Example 7 71 parts of isobutanol, 8.7 parts of Water, 0.2 part of a 50percent aqueous nickel bromide solution and 0.1 part ofcopper-(ID-bromide are treated in a shaking autoclave at 45 atmospherespressure and at 190 C. with mixed gas for 12 hours. The reaction product(106 parts) is pale brown. By distillation in vacuo there are obtainedtherefrom 99 parts of a colorless distillate which contains 4.2 per-centof acrylic acid and 52.6 percent of isobutyl acrylate besides 7 parts ofa red-brown oily residue.

Example 8 A mixture of 73 parts of normal butanol, 6.7 parts of water,0.2 part of a 50 percent nickel-2-bromide solution, 0.1 part ofcopper-(l)-iodide is treated with mixed gas for 12 hours as described inExample 7. 102 parts of a pale yellow product are obtained. Bydistillation there can be obtained therefrom 97 parts of a colorlessdistillate which contains 2.7 percent of acrylic acid and 43 percent ofbutyl acrylate, besides 5 parts of a brown oily residue. If the aboveprocedure is followed with a mixture which contains the same catalystcomponents but 79.7 parts of normal butanol without the addition ofwater, there are obtained 81 parts of a dark brown product whichcontains only 3.6 percent of butyl acrylate.

This application is a continuation of application Serial No. 714,494,filed February 11, 1958, and now aban doned.

What we claim is:

1. In a process for the production of acrylic acid esters by theinteraction of acetylene, carbon monoxide and lower alkanols at atemperature of between 100 and 250 C. and at a pressure of between 5 and80 atmospheres, the improvement which comprises carrying out thereaction with an initial reaction medium of said lower alkanolcontaining from 4 to 12 percent by weight, with reference to the amountof the lower alkanol, of water, 0.1 to 1 percent by weight, withreference to the amount of the lower alkanol, of a catalyst consistingessentially of nickel ions and halogen ions, said halogen being selectedfrom the group consisting of chlorine, bromine and iodine and 3 to 20percent by weight, with reference to the amount of the catalyst of aheavy metal as activator, said heavy metal being selected from the groupconsisting of copper, mercury, zinc, cadmium, lead, and chomium, and inthe absence of an inert organic solvent but in the presence of acrylicacid which is formed during the reaction from said water in the reactionmedium.

2. In a process for the production of acrylic acid esters by theinteraction of acetylene, carbon monoxide and lower alkanols at atemperature of between 100 and 250 C. and at a pressure of between and80 atmospheres, the improvement which comprises carrying out thereaction with an initial reaction medium of said lower a1- kanolcontaining from 4 to 12 percent by weight, with reference to the amountof the lower alkanol, of water, 0.01 to 1 percent by weight, withreference to the amount of the lower alkanol, of a nickel halideselected from the group consisting of nickel chloride, nickel bromideand nickel iodide and 3 to 20 percent by weight, with reference to theamount of the nickel halide, of a heavy metal compound as activator,said heavy metal being selected from the group consisting of copper,mercury, zinc, cadmium, lead, and chromium, and in the absence of aninert organic solvent but in the presence of acrylic acid which isformed during the reaction from said water in the reaction medium.

3. In a process for the production of acrylic acid esters by theinteraction of acetylene, carbon monoxide and lower alkanols at atemperature of between 100 and 250 C. and at a pressure of between 10and 80 atmospheres, the improvement which comprises carrying out thereaction with an initial reaction medium of said lower alkanolcontaining from 4 to 12 percent by weight, with reference to the amountof the lower alkanol, of water, 0.01 to 1 percent by weight, withreference to the amount of the lower alkanol, of a nickel halideselected from the group consisting of nickel chloride, nickel bromideand nickel iodide and 3 to 20 percent by weight, with reference to theamount of the nickel halide, of a copper compound as an activator, andin the absence of an inert organic solvent but in the presence ofacrylic acid which is formed during the reaction from said water in thereaction medium.

4. In a process for the production of acrylic acid esters by theinteraction of acetylene, carbon monoxide and lower alkanols at atemperature of between 100 and 250 C. and at a pressure of between 10and 80 atmospheres, the improvement which comprises carrying out thereaction with an initial reaction medium of said lower alkanolcontaining from 4 to 12 percent by weight, with reference to the amountof the lower alkanol, of water, 0.01 to 1 percent by weight, withreference to the amount of the lower alkanol, of a nickel halideselected from the group consisting of nickel chloride, nickel bromideand nickel iodide and 3 to 20 percent by weight, with reference to theamount of the nickel halide, of a copper halide selected from the groupconsisting of copper chloride, copper bromide and copper iodide asactivator,

and in the absence of an inert organic solvent but in the presence ofacrylic acid which is formed during the reaction from said water in thereaction medium.

5. In a process for the production of acrylic acid esters by theinteraction of acetylene, carbon monoxide and lower alkanols at atemperature of between 100 and 250 C. and at a pressure of between 10and atmospheres, the improvement which comprises carrying out thereaction with an initial reaction medium of said lower alkanolcontaining from 4 to 12 percent by weight, with reference to the amountof the lower alkanol, of water, 0.01 to 1 percent by weight, withreference to the amount of the lower alkanol, of nickel-2-bromide and 3to 20 percent by weight, with reference to the amount of nickel-2-bromide, of copper iodide as activator, and in the absence of an inertorganic solvent but in the presence of acrylic acid which is formedduring the reaction from said water in the reaction medium.

6. An improved process for the production of normal butyl acrylate bythe interaction of acetylene, carbon monoxide and normal butanol atelevated temperature and at superatmospheric pressure in the absence ofan inert organic solvent, which comprises carrying out the reaction inan initial reaction medium of said butanol containing 0.01 to 1 percentby weight, with reference to the amount of normal butanol, of nickelbromide and of 3 to 20 percent by weight, with reference to the amountof nickel bromide, of copper iodide, and of 4 to 12 percent by weight,With reference to the amount of normal butanol, of water from whichacrylic acid is formed during the reaction.

7. An improved process for the production of ethyl acrylate by theinteraction of acetylene, carbon monoxide and ethyl alcohol at elevatedtemperature and at superatmospheric pressure in the absence of an inertorganic solvent, which comprises carrying out the reaction in an initialreaction medium of said ethyl alcohol containing 0.01 to 1 percent byweight, with reference to the amount of ethyl alcohol, ofnickel-2-bromide and of 3 to 20 percent by weight, with reference to theamount of nickel-2-bromide, of copper bromide and of 4 to 12 percent byWeight, with reference to the amount of normal lbutanol, of water fromwhich acrylic acid is formed during the reaction.

8. In a process for the production of acrylic acid esters by theinteraction of acetylene, carbon monoxide and a lower alkanol containing1 to 4 carbon atoms at a temperature of between about and 250 C. and apressure between 5 and 80 atmospheres in the presence of minor amountsof a catalyst consisting essentially of nickel and halogen, said halogenbeing selected from the group consisting of chlorine, bromine andiodine, and in the presence of a heavy metal activator, said heavy metalbeing selected from the group consisting of copper, mercury, zinc,cadmium, lead, chromium, and the halides of said heavy metal compounds,the improvement which comprises carrying out the reaction substantiallyin the absence of an inert organic solvent but in the presence of about4 to 22% of water, said water being converted during the process intoacrylic acid in the reaction medium.

References Cited in the file of this patent UNITED STATES PATENTS2,582,911 Neher et al. Jan. 15, 1952 2,883,418 Reppe et al Apr. 21, 1959FOREIGN PATENTS 854,948 Germany Nov. 10, 1952 1,093,117 France May 2,1955

1. IN A PROCESS FOR THE PRODUCTION OF ACRYLIC ACID ESTERS BY THEINTERACTION OF ACETYLENE, CARBON MONOXIDE AND LOWER ALKANOLS AT ATEMPERATURE OF BETWEEN 100 AND 250*C. AND AT A PRESSURE OF BETWEEN 5 AND80 ATMOSPHERES, THE IMPROVEMENT WHICH COMPRISES CARRYING OUT THEREACTION WITH AN INITIAL REACTION MEDIUM OF SAID LOWER ALKANOLCONTAINING FROM 4 TO 12 PERCENT BY WEIGHT, WITH REFERENCE TO THE AMOUNTOF THE LOWER ALKANOL, OF WATER, 0.1 TO 1 PERCENT BY WEIGHT, WITHREFERENCE TO THE AMOUNT OF THE LOWER ALKANOL, OF A CATALYST CONSISTINGESSENTIALLY OF NICKEL IONS AND HALOGEN IONS, SAID HALOGEN BEING SELECTEDFROM THE GROUP CONSISTING OF CHLORINE, BROMINE AND IODINE AND 3 TO 20PERCENT BY WEIGHT, WITH REFERENCE TO THE AMOUNT OF THE CATALYST OF AHEAVY METAL AS ACTIVATOR, SAID HEAVY METAL BEING SELECTED FORM THE GROUPCONSISTING OF COPPER, MERCURY, ZINC, CADMIUM, LEAD, AND CHOMIUM, AND INTHE ABSENCE OF AN INERT ORGANIC SOLVENT BUT IN THE PRESENCE OF ACRYLICACID WHICH IS FORMED DURING THE REACTION FROM SAID WATER IN THE REACTIONMEDIUM.